Temporalis Muscle Transposition

Introduction

The pedicled temporalis muscle flap is a very versatile, local, axial flap with many uses in craniofacial reconstruction (e.g., orbital cavity augmentation following exenteration, coverage of a temporal/subtemporal calvarial defect, maxillectomy augmentation, hemipalatectomy reconstruction, and mastoid/temporal defect reconstruction). As a moderately bulky flap with a good range of rotation, it allows for the reliable reconstruction of a variety of sites. In particular, it is the only local flap adequate in bulk and surface area for reconstruction following maxillectomy or unilateral palatomaxillectomy. It can be used to reconstruct the cranial base or to cover mesh or plates used to repair at the cranial base, temporal bone, or orbital rim. The flap has a sufficiently robust blood supply that it can be split into anterior and posterior paddles by bisecting the muscle along its fibers from its origin to the level of the zygomatic insertion. In this way, the muscle can actually be used as two separate flaps, connected to a common blood supply from the deep temporal artery. Bilateral flaps can be harvested to permit larger reconstructions that cross the midline.

Key Operative Learning Points

Vascularized flaps are the reconstruction modality of choice. Compared with free flaps, pedicled local flaps require less time, involve less morbidity of the donor site, and do not require microvascular expertise.
Preoperative embolization or intraoperative oncologic resection can disrupt the blood supply to this flap and render it nonviable.
Injury to the frontotemporal branch of the facial nerve is avoided by careful dissection at the level of the adipose tissue pad, taking care to leave the superficial layer of the deep temporalis fascia up with the skin flap.
A superficial temporalis fascia flap may be raised along with the muscle for extended defects; if this is done, care should be taken to preserve the separate blood supply to the temporoparietal fascial flap.

Preoperative Period

History

Proper patient selection is imperative in deciding to use this flap. Although it is robust and applicable to many regional defects, this flap should not be used in cases where its internal maxillary or deep temporal blood supply has been compromised.
A thorough history will often reveal patients who may not be appropriate candidates for the use of this flap. Examples include patients who have had embolization of the ipsilateral internal maxillary artery, those who have had extensive dissection along the medial surface of the muscle, cases where excision of the muscle was required, or those where the external carotid artery had to be sacrificed.

Physical Examination

Thorough examination of the head and neck to gauge extent of tumor and size of anticipated defect
Examine the neck and scalp for evidence of previous surgery that could compromise the blood supply to the flap.
Examine the temporal region to evaluate the bulk of temporalis muscle.

Imaging

Careful preoperative review of computed tomography (CT) and magnetic resonance imaging (MRI) is necessary to make sure that the vasculature to the flap will not be compromised during tumor resection.
Special care must be taken with patients who have malignancies of the maxillary sinus, where the tumor may have penetrated the posterior confines of the maxillary sinus cavity. Tumor contamination of the infratemporal fossa in such cases can result in compromise of the deep temporal artery, precluding the use of this muscle as the reconstructive flap. This situation must be recognized preoperatively, as there are no local “backup” flaps for palatomaxillary repair when the deep temporal is resected and the temporal artery is not usable; that is, a free tissue transfer is the only other reconstructive option in such situations.

Indications

For craniofacial reconstruction—that is, augmentation of the orbital cavity following exenteration, coverage of a temporal/subtemporal calvarial defect, maxillectomy augmentation, hemipalatectomy reconstruction, and reconstruction of a mastoid/temporal defect
Secondary to its bulk and surface areas, this flap has particular utility for reconstruction following maxillectomy or unilateral palatomaxillectomy.
It may be used to reconstruct the cranial base or to cover mesh or plates used for repair at the cranial base, temporal bone, or orbital rim.

Contraindications

The temporalis muscle flap cannot be used if there has been previous disruption of its blood supply (e.g., preoperative embolization) or when anticipated resection would disrupt the blood supply.
It should not be used if the patient is unwilling to accept a temporary cosmetic deformity due to repositioning of the muscle and subsequent temporal hollowing (patients are counseled that this defect can be repaired at a later stage).

Preoperative Preparation

Patients should be counseled that the harvesting of this flap will result in a potentially significant concave deformity over the temporal fossa. This deformity can be augmented in a secondary procedure whereby adipose tissue, hydroxyapatite cement, or silicone/polymeric implants are used to fill this potentially substantial deformity. Following augmentation, the aesthetic results are usually excellent.

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